Air Pollution Impacts

Grand Teton National Park

Natural and scenic resources in Grand Teton National Park (NP) are susceptible to the harmful effects of air pollution. Nitrogen, sulfur, ozone, toxic air contaminants, and fine particles impact natural resources such as wildlife, surface waters, and vegetation, and scenic resources such as visibility. Click on the tabs below to learn more about air pollutants and their impacts on natural and scenic resources at Grand Teton NP.

Nitrogen & Sulfur

Toxics & Mercury

Ozone

Visibility

Over 50% of high elevation lakes at Grand Teton NP are estimated to be sensitive to some degree of atmospheric deposition (Nanus et al. 2009).

Nitrogen and sulfur compounds deposited from air pollution can harm surface waters, soils, and vegetation. High elevation ecosystems in the park are particularly sensitive to sulfur and nitrogen deposition. Not only do these systems receive more deposition than lower elevation areas because of greater amounts of snow and rain, but short growing seasons and shallow soils limit the capacity of soils and plants to buffer or absorb sulfur and nitrogen. High elevation lakes, especially, are sensitive to acidification from sulfur and nitrogen deposition and excess nitrogen enrichment. Acidification may cause loss of sensitive macroinvertebrates and fish, while enrichment may alter lake diversity. Alpine plant communities are also vulnerable to nitrogen enrichment, which may favor some species at the expense of others.

Effects of nitrogen and sulfur deposition at Grand Teton NP include:

Concentrations of ammonium in wet deposition from regional agricultural sources are elevated and increasing at sites in or near to the park (NPS 2010 [pdf, 2.8 MB]; Ingersoll et al. 2007; Clow et al. 2003);

Measurements indicate higher atmospheric nitrogen (N) inputs to the north of the park and lower levels to the south—a gradient reflected in nitrogen concentrations in rain and snow, soils, and plants (Van Miegroet 2010).

How much nitrogen is too much?

Nitrogen is a fertilizer and some nitrogen is necessary for plants to grow. However, in natural ecosystems, too much nitrogen disrupts the balance of plant communities, promoting the growth of weedy species at the expense of slower-growing species. Alpine areas are particularly sensitive, as short growing seasons, cold temperatures, and thin soils limit the amount of nitrogen that can be assimilated. A recent spatial analysis identified high elevation lakes and alpine vegetation communities at Grand Teton NP as being at high risk from nitrogen enrichment (Sullivan et al. 2011a; Sullivan et al. 2011b [pdf, 12 MB]). In other high elevation ecosystems in the Rocky Mountains, this shift to a more disturbed, polluted system in alpine lakes occurred at nitrogen wet deposition loading of about 1.5 kilograms per hectare per year (kg/ha/yr) (Saros et al. 2010; Baron 2006). Changes in plant species composition in alpine vegetation communities in the Rocky Mountains occurred at about 4 kg/ha/yr of wet plus dry nitrogen (Bowman 2006). Research is currently underway to examine whether similar shifts have occurred at Grand Teton NP (Spaulding 2009; Van Miegroet 2010), and to define the amount of deposition, or the “critical load,” at which these shifts occur. Critical loads for aquatic and terrestrial resources can be used to establish goals for ecosystem protection or recovery.

Elevated levels of pesticides and other contaminants have been detected in ecosystem indicators such as lichens (Letharia vulpina, above) at Grand Teton NP, Wyoming.

Toxics, including heavy metals like mercury, accumulate in the tissue of organisms. When mercury converts to methylmercury in the environment and enters the food chain, effects can include reduced reproductive success, impaired growth and development, and decreased survival. Other toxic air contaminants of concern include pesticides, industrial by-products, and emerging chemicals such as flame retardants for fabrics. Some of these chemicals are known or suspected to cause cancer or other serious health effects in humans and wildlife.

While ground-level ozone concentrations are generally low at Grand Teton NP, Wyoming, there are a few ozone-sensitive species present in the park, such as spreading dogbane (Apocynum androsaemifolium).

Naturally-occurring ozone in the upper atmosphere absorbs the sun’s harmful ultraviolet rays and helps to protect all life on earth. However, in the lower atmosphere, ozone is an air pollutant, forming when nitrogen oxides from vehicles, power plants, and other sources combine with volatile organic compounds from gasoline, solvents, and vegetation in the presence of sunlight. In addition to causing respiratory problems in people, ozone can injure plants. Ozone enters leaves through pores (stomata), where it can kill plant tissues, causing visible injury, or reduce photosynthesis, growth, and reproduction.

Human-caused haze and fine particles of air pollution sometimes reduce visibility of such scenic vistas at Grand Teton NP, Wyoming.

Visitors come to Grand Teton NP to enjoy spectacular views of the windswept granite of the Teton Range, mountain lakes, and the Jackson Hole valley floor. Unfortunately, such park scenic vistas are sometimes obscured by haze caused by fine particles in the air. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze and visibility impairment. Additionally, organic compounds, soot, and dust reduce visibility. Smoke from nearby forest fires also significantly contributes to particulate matter in the region.

In the region, average natural visual range is reduced from about 180 miles (without the effects of pollution) to about 120 miles because of pollution. The visual range is reduced to below 70 miles on high pollution days (IMPROVE 2010).